This invention relates to determining toner usage in an imaging device having a photoconductive roller that receives toner from a developer roller.
Automatic determination of toner usage is useful both to signal an operator when the hopper or other source of toner is empty or approaching empty, and, similarly, to signal the operator when a chamber of toner cleaned from the photoconductor is full or approaching full.
Measurement of toner used by counting pels is well known. (Pels are dots or other small picture elements.) This invention employs counting pels as a major element of it determination of usage. However, employing only pel counting does not account for start and end of imaging device operation nor for blank or near blank pages made by the imaging device.
Typically, at start up several cycles of rotation of the photoconductor occur and, although ideally no toner would be used, this invention recognizes that, in total, a nontrivial amount of toner is used with such blank operations. Also, when an image has very light pet usage, this invention recognizes that, in total, a significant amount of toner is used in printing such near blank or blank pages.
Additionally, a number of operating factors of the imaging device may be used to scale the results from pet applications and blank operations.
This invention is directed to imaging devices, which are controlled by electronic data processing and to imaging based on pels (small picture elements). Such digital imaging devices are now widely available as printers and copiers and the like.
In this invention the number of pels imaged is determined and that number is multiplied by at least one pel weight factor. Similarly the amount of photoconductor rotation during non-imaging operation is determined and that amount is multiplied by at least one rotation weight factor.
In specific implementations the weight factors may vary over usage as the amount of toner usage varies with different darkness settings of the imaging device, different process speeds, different resolutions for printing, different papers or other media being imaged, and different ambient conditions, and with exceptionally high coverage imaging and with the amount of previous toner used from an unreplenished source. Accordingly the weight factors reflecting these are better applied with each page printed or revolution of the photoconductive roller.
Additionally, a factor of essentially 1, which may be termed an adjustment factor, is initially applied, and that factor may be changed for future operations, based on actual experience. The adjustment factor can be stored in memory on a replaceable toner cartridge, from which it is obtained by the printer on which the cartridge is installed.
The exact weight factors and how many different factors are employed depend on the specific characteristics of the imaging device and are obtained by actual tests on representative imaging devices. Accordingly, exact values for a specific device are incidental to this invention.
The factors may vary moderately when the ultimate result is for determination of the amount of toner in the cleaner chamber rather than for the amount of toner used from the toner supply.